U.S. Pat. No. 7,048,195 B2 relates to a method and system for expiring a device after a predetermined time period has elapsed. The device uses its own time cell so that the elapsed time is not altered through external time source. A charge storage element in the time cell includes floating gate field effect transistor, wherein the floating gate field effect transistor is configured within the time cell such that the floating gate field effect transistor turns on in response to applying power to the time cell after a predetermined time period has elapsed.